ACARIDJB. 665 



genus Cheyletus is remarkable for having the maxillae very large, 

 and like a pair of legs, with the ends tripartite, the outer 

 division being curved and clawlike, while the two innermost 

 are slender lobes pectinated on the inner side ; the mandibles 

 are style-like. A European species (Fig. 640) feeds on Cheese- 

 mites. It is thought by Mr. R. Beck that another species of 

 Cheyletus is parthenogenous, as "he obtained several genera- 

 tions from the first individual, without the intervention of a 

 male." (Science-Gossip, 1869, p. 7.) Mr. J. H. Gregory, of 

 Marblehead, Mass., has found a species of this genus, which we 

 may call Cheyletus seminivorus (Plate 13, fig. 6). It injured the 

 seeds of the cabbage stored up during the winter by sucking 

 them dry. The genus Tyroglyplms is known l>y the body being 

 elongated oval, with scissor-like mandibles, and outstretched 

 four-jointed feet, with a long stalked sucking disc at the end. 

 T. domesticus DeGeer is in Europe common in houses. 



Many people have been startled by statements in newspapers 

 and more authoritative sources, as to the immense numbers of 

 sugar mites, T. sacchari (Fig. 641), found 

 in unrefined or raw sugar. According to 

 Professor Cameron, of Dublin, as quoted 

 in the "Journal of the Franklin Insti- 

 tute," for November, 1868, "Dr. Hassel 

 (who was the first to notice their general 

 occurrence in the raw sugar sold in Lon- 

 don) found them in a living state in no 

 fewer than sixty-nine out of seventy-two 

 samples. He did not detect them in a 

 single specimen of refined sugar. In an Flg> 641> 



inferior sample of raw sugar, examined in Dublin by Mr. 

 Cameron, he reports finding five hundred mites in ten grains 

 of sugar, so that in a pound's weight occurred one hundred 

 thousand. They appear as white specks in the sugar. The 

 disease known as grocer's itch is, undoubtedly, due to the 

 presence of this mite, which, like its ally the Sarcoptes, works 

 its way under the skin of the hand, in this case, however, of 

 cleanly persons. 



Closely allied to the preceding is the Cheese-mite, T. siro 

 Linn., which often abounds in newly made cheese. Lyonnet 



